Slack controller



May 1 l, 1943.

p2 INVENTOR BY I a mil m A ORNEYS Patented May 11, 1943 SLACK CONTROLLER John L. Spence, Jr., Brooklyn, N. Y., assignor to Leventhal Patents, Inc., New York N. Y., a corporation of Delaware Application May 31 1941, Serial No. 396,094"

6 Claims. (Cl. 88-1837) This invention relates to a slack controller for endless loops of motion picture film.

In continuous motion picture projectors, such as those used for advertising purposes, a length 10f film is repeatedly projected. The film is in the form of an endless loop and for the purpose of conserving space the film usually is in the form of a coil supported on rollers. An endless loop of film wound in a coil has the difficulties that the layers may be wound too tight or too loose and that when properly wound for one condition of the film, it will not necessarly be properly wound for another condition. If the film becomes too tightly wound, it will break, whereas if it is too loosely wound, it will'not wind up on the coil properly.

An object of this invention is mechanism for, controlling the internal peripheral length of the coil so as to maintain a predetermined extent of slack and thereby maintain uniform conditions in the coil.

Other objects, novel features and advantages of this invention will become apparent from the following specification and accompanying drawing, wherein the single figure is a diagrammatic illustration of mechanism embodying the invention.

An endless loop of film in the general form.

of a coil I 0 is supported by a roller l I with the the film passes around a guide roller l5 and? roller i6 supported at the free end of the lever l3. From the roller IS, the film passes upwardly to an idler guide roller I! located above the roller i6 and from thence to a projector fee'd roller i8. From the projector roller l8. the film passes through the usual film gate i9 and to a second projector feed roller 20, from which it passes back to the coil iii to form the outer layer thereof. The projector rollers l8 and 20 are driven in the usual manner by suitable means (not shown), in timed relationship. 1

The rollers ii, i2, i5, i6 and ii are mounte for free rotation and rotation thereof is eiiected by linear movement of the film produced by the projector rollers i8 and 20. The lever i3 is biased to tend to cause movement of the roller llaway from the roller ii either by gravity or by a spring 2i. The spring 2| is used onlv when the arrangement is such that the lever I3 is not gravity biased or the weight oi the lever and roller I6 is insuiflcient to supply the required degree of bias.

The inner periphery of the film coil is determined by the tension exerted on the film by k the projector feed roller it. 'When the tension on that portion of the film between the rollers l6 and I1 exceeds the bias exerted on the lever l3, the lever i3 swings counterclockwise to move the roller l2 toward the roller ii. thereby decreasing the internal periphery of the coil and supplying more slack thereto. When the tension on the film between the rollers l6 and I1 is exceeded by the bias applied to the arm l3, said arm swings clockwise, thereby moving the roller l2 away from the roller ii to increase the internal periphery of the coil so that the coil will take up the slack produced by the decrease in tension.

In View of the fact that the Single figure of the drawing is diagrammatic, the film gate appears to be in the same plane with the film coil, but it is to be understood that in a commercial embodiment of the invention the film gate is so arranged as to permit proper projection without interference with or by the remainder of the'apparatus. Also, since the particular form of projector has no bearing on the invention, all illustration of a projector except the film gate has been omitted for the sake of simplifying the drawing.

I claim: 1. In combination, an endless loop of film i the form of a coil, a first roller and a second roller contacted by the inner turns of said coil, means supporting said second. roller for movement relative to said first roller with said sec ond roller being biased to move it away from said first roller, 9. third roller supported for movement with said second roller and film feed ing means, said film passing from the inner coil of said endless loop to the outer coil thereof around said third roller and through said feeding means.

2. In combination, an endless loop of film i the form of a coil, a first roller and a second roller contacted by the inner turns of said coil. a lever supporting said second roller and biased to move said second roller away from said first. roller, 9. third roller supported by said lever, and film feeding means, said film passing from-the inner coil of said endless loop to the outer coil thereof around said third roller and through said feeding means.

3. The combination according to claim 1 characterized by the supporting means for said second roller being gravity biased.

4. The combination according to claim 1 characterized by the supporting means for said second roller being spring biased.

5. The combination according to claim 2 v characterizedby said lever being gravity biased.

6. The combination according to claim 2 characterized by said lever being spring biased.

JOHN L. SPENCE, JB. 

